Type bar action



p 1965 A. R. JOHNSON 3,207,283

TYPE BAR ACTION Filed July 16, 1962 2 Sheets-Sheet 1 INVENTOR ARTHUE.JOljNSON M5 fi \3Q&.Q,L-%

ATTORNEYS Sept. 21, 1965 A. R. JOHNSON TYPE BAR ACTION 2 Sheets-Sheet 2Filed July 16, 1962 V NT R ARTI- IP IR R. 9OHNSON g, ATTORNEYS UnitedStates Patent 3,207,283 TYPE BAR ACTION Arthur R. Johnson, Wethersfield,Conn., assignor to Royal McBee Corporation, New York, N.Y., acorporation of .New York Filed July 16, 1962, Ser. No. 209,851 9 Claims.(Cl. 197-17) This invention relates to a type bar action for controllingthe deceleration of a type bar on its return stroke to the headrest.

Conventional power driven writing machines of the basket type arecommonly characterized by a headrest against which the type bar strikesat the end of its return stroke after making an imprint. A spring iscustomarily used to effect such return stroke. In order to attain highspeed typing, such a spring must be relatively powerful in order toclear the type bar from a position near the platen so as to make way forthe imprint stroke of a succeeding bar to preclude jamming of two barsat or near the printing position. The force of impact of a returning baron the headrest is a function of the tension or power of the returnspring, the greater the tension at the start of the return stroke, thegreater the impact on the headrest at the end of the return stroke.Hence if a very strong spring is used, the impact will be correspondingyhigh resulting in a high rebound reaction of the bar upon hitting theheadrest. Various headrest cushioning expedients are resorted to in aneifort to absorb the impact energy of the returning bar to preventexcessive rebounding thereof and to reduce noise. It has been found,however, that there is a limit to the amount of cushioning that can beprovided in a headrest and that limit is directly related to the maximumreturn spring tension that can be used. Thus there is a definitelimitation placed on typing speed which limitation may be, and often is,well below the printing capacity of the machine.

In high speed operation of a power driven writing machine, energy isexpended by the machines power roll in driving the type bar to printingposition. Where a spring is used to return the bar, a good portion ofthe springs return energy is supplied to the spring by the power rollduring the type bar printing stroke. This energy is transferred from thespring to the bar during the bars return and is ultimately absorbed ordissipated by the headrest and is not returned to the power roll. Hencethe speed of the power roll is inclined to fluctuate which notinfrequently results in non-uniform printing impression.

It is accordingly among the objects of my invention to provide a typebar deceleration mechanism that overcomes the above mentioneddisadvantages in a thoroughly practical and efiicient manner.

Another object is to provide a mechanism of the above nature whereintype bar rebound is completely eliminated. A still further object is toprovide such a mechanism whereby much higher type bar return speeds maybe used thus making possible a substantial increase in typing speed.Another object is to provide a mechanism of the above nature wherein theenergy supplied to the type bar to effect its return is returned to thedrive source for use in the next typing cycle thus to maintain the driveroll speed constant regardless of the typing speed and to attain moreuniform type impression. Other objects will be in part apparent and inpart pointed out herein below.

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In the drawing wherein I have shown two embodiments of my invention andwhereinsimilar reference characters refer to similar parts throughoutthe several views:

FIGURES 1-5 are schematic views showing the condition of the mechanismat Figure Normal position 1 Start of acceleration 2 End of acceleration3 Free flight 4 Start of deceleration- 5 FIGURES 6-10 are schematicviews of a modified form of the mechanism showing its condition atReferring now to FIGURE 1 a power roll 20 is rotatably mounted on themachine frame F to be driven in the conventional manner. A type baractuating arm 21 is pivotally mounted on a cross shaft 22 carried by themachine frame and is under the clockwise bias of a return spring 23whose opposite ends are connected to the arm and frame respectively. Oneend of a link 24 is pivotally connected to the upper end of arm 21, theother end of the link being pivotally connected to one end of a type bar25 rockably mounted on a pivot 26 and normally lying against a headrest27 which may or may not be cushioned as desired. Thus when arm 21 isrocked counterclockwise, in a manner to be described, type bar 25 isswung clockwise to printing position (see FIGURE 4). After printing, thetype bar and arm are returned to normal position (FIGURE 1) by returnspring 23.

Arm 21 carries between its ends a pin 28 on which are pivotally mounteda type bar drive accelerating cam 29 and a type bar return deceleratingcam 30, these cams being provided with power roll engaging surfaces 29aand 30a. Edge 29b of cam 29 normally rests against a stop 31 on arm 21against which it is held by the clockwise bias of a cam return spring32. A trigger lip 33 projects from the face of cam 29 and overlies thenose 34a of a trigger 34 pivotally mounted on a pin 35. Trigger 34 isoperatively associated in any suitable manner with the key lever (notshown) which corresponds with type bar 25. It may now be seen that whensuch key lever is depressed trigger 34 is rocked counterclockwise sothat its nose 34a forces lip 33 upward causing cam 29 to pivotcounterclockwise to the FIGURE 2 position where point A of its surface29a engages the surface of power roll 20 whereby acceleration of the camis started. Point A lies on or closely adjacent to a line passingthrough the axes of cam 29 and power roll 20. Acceleration of cam 29ends when point B on its surface 29a quits engagement with the surfaceof power roll 20 (see FIGURE 3). It should be noted that as the cam isaccelerated from zero to full velocity its point of contact moves awayfrom the line passing through the axes of the cam and power roll in adirection opposite to the direction of rotation of the power roll asindicated by the broken line arrow in FIGURE 3. This assures completecontrol of the cams acceleration.

When the cam 29 reaches its FIGURE 3 position at the end ofacceleration, arm 21 and type bar 25 have reached their middle positionand start their free flight which continues to the FIGURE 4 position,the printing position of the type bar. An over-centering spring 37 hasone end connected to cam 30 and its other to arm 21, the connectionsbeing so located that the spring normally biases edge 30b of the camcounterclockwise (FIGURE 1) against a stop 38 on arm 21 thus to limitcounterclockwise movement of the cam. However, when the cam reaches theend of its acceleration (FIGURE 3) its edge 30b engages a framesupported reset stop 39 which, upon the continuing free flight of arm 21causes the spring 37 to overcenter thus to rock the cam clockwise to itsFIGURE 4 position wherein it is held by the stud 37a on cam 30, to whichthe upper end of spring 37 is attached, bearing against the top of cam29.

The FIG R 4 it an f the mech n s marks the d o f e fli ht n h a t f ther t drive n e the pu l of urn s n 23 wh h wa t s an during theacceleration and ree fl ht ar isans 9f h l Thus when cam 30 reaches theFIGURE position which marks the start of deceleration point C on itssurface 30a engages the surface of power roll 20, Point C being spacedfrom the line passing through the axes of cam 30 and roll in thedirection of rotation of the roll. As arm 21 continues its clockwisemovement under the pull of spring 23 cam is rocked count'erclockwise atits point of engagement with the power roll moves from point C (FIGURE5) to point D (FIGURE 1) which is closely adjacent to or on the 'linepassing through the axes of the cam and roll; thus the point of contactmoves in a direction opposite to the direction of rotation roll 20 toprovide complete and unlimited control of deceleration of type bar 25.As cam 30 moves counterclockwise from its FIGURE 5 to its FIGURE 1position, spring 37 again overcenters so that the cam comes to rest inits normal position against stop 38 on arm 21. Also cam 29 is returnedto its normal position where its lip 33 overlies trigger nose 34a, thetrigger having been returned to its normal position against a stop 34bby a trigger spring 340.

From the foregoing it may be seen that return spring 23 may be morepowerful than a conventional spring of this nature because of thecomplete deceleration control described. As the deceleration iscontrolled from maximum to zero velocity, type bar 25 comes to restagainst headrest 27 when its velocity is zero or substantially so, theenergy of the type bar being returned to power roll 20 through cam 30.Thus no type bar rebound is possible, higher speed typing is madepossible and uniform type impression is attained.

In the modified form of the invention shown in FIG- URES 6-10 a type baractuating arm is pivotally mounted on a cross shaft 51 carried by themachine frame and has attached to the upper end thereof one end of areturn spring 52 and one end of a type bar operating link 53. The otherend of return spring 52 is attached to the machine frame and accordinglybiases arm 50 clockwise toward power roll 20. When arm 50 is driven tothe left by roll 20, in a manner to be described, type bar 25 is rockedto printing position as noted above in connection with FIGURES 1-5.

A roll cam, generally indicated at 54 is rotatably mounted on a pin 55carried by arm 50 between its upper end and axis. Cam 54 is providedwith a curved accelerating surface 54a which may extend from a point Ato a point B thereon, the cam also having a decelerating surface 54bwhich may extend from a point C to a point D, surfaces 54a and 54b beingjoined by a fiat 54c whose radii are less than those of surfaces 54a and541) at points A and C respectively. A pair of lips 56 and 57 extendfrom one surface of cam 54, lip 56 being engaged by the nose 58a of atrigger 58 to latch the cam in its rest or normal FIGURE 6 position.Trigger 58 is pivotally mounted on a cross shaft 59 carried by themachine frame and has an arm 58b operatively associated in any suitablemanner with a keylever (not shown) whereby upon depression of suchlever, trigger 58 is rocked clock wise to unlatch the trigger nose 58aand cam lip 56.

An overcentering spring 60 has one end connected to cam 54 at a point60a, the other end of the spring being connected to a finger 61 which.is preferably integral with arm 50. When cam 54 is in its normal FIGURE6 position spring 60 biases cam 54 counterclockwise so that trigger lip56 bears against trigger nose 58a which accordingly holds the cam withits flat 54c spaced from the driving surface of power roll 20. Whentrigger 58 is actuated by a key lever its nose 58a is withdrawn from infront of lip 56 permitting spring 61 to rotate cam 54 counterclockwiseto its FIGURE 7 position wherein point A on its accelerating surface54;: engages the power roll to start the acceleration portion of thecycle.

As cam 54- is driven by the power roll from its FIG- URE 7 to its FIGURE8 position which latter position marks the end of acceleration, arm 50is rocked counterclockwise and is accelerated to its maximum velocity asis also the type bar. It will be noted that the point of engagement Abetween the cam and roll lies on or closely adjacent to a line passingthrough the axes of the cam and roll and that at the end of accelerationat point B the point of engagement has moved in a direction opposite tothe direction of rotation of power roll 20 thus providing complete andunlimited control of acceleration of arm 50. The energy xpended by thepower roll in driving and accelerating arm 50 is stored in return spring52.

As noted above when the mechanism is in its FIG- URE 8 position theacceleration portion of the cycle ends and the parts are in free flightto their FIGURE 9 position wherein the type bar is in printing positionand makes an impression. As described above, arm 50 is provided withprojecting lip 57 which is adapted to strike a cam reset 63 at the startof the-free flight portion of the cycle (FIGURE 8). When this occurs cam54 is rocked clockwise about its pivot 55 causing spring 60 toovercenter and rock the cam until its lip 56 engages a stop 64. In themeantime return spring 52 has swung arm 50 from its end of free flightposition (FIGURE 9) to its start of deceleration position (FIGURE 10)where point C on cam surface 54b engages roll 20 at a point spaced fromthe line passing through the cam and roll axes in the same direction asthat of roll rotation.

Deceleration of arm 50 and accordingly its associated type bar iseffected as the point of engagement of cam surface 54b and roll 20 movesfrom C to D, it being noted that the direction of this movement isopposite to that of roll rotation to afford completely controlleddeceleration. As this movement continues the energy that was stored inreturn spring 52 is returned to roll 20 thus maintaining the roll speedconstant and affording uniform type impression. As the velocity of arm50 is decelerated to zero or practically so at the end of deceleration(FIGURE 6) type bar 25 comes to rest against headrest 27 atsubstantially zero velocity thus precluding any possibility of rebound.Also movement of cam 54 from the FIGURE 10 to the FIGURE 6 positioncauses spring 60 to overcenter again so that trigger nose 58a and camlip 56 relatch with cam flat 54c opposed to and spaced from the drivingsurface of power roll 20.

It will now appear that I have provided a mechanism for controlling thedeceleration of a type bar that attains the several objects set forthabove in a thoroughly practical and eflicient manner.

As other embodiments of the invention are possible and as changes can bemade in the ones disclosed, all without departing from the scope of theinvention, it is to be understood that the foregoing is to beinterpreted as illustrative and not in a limiting sense.

I claim:

I. A type bar action for a writing machine in combina tion,

a frame.

a type bar pivotally mounted on said frame,

a hea-drest on said frame for said bar,

means including a pivoted actuating arm for pivoting said bar from saidheadrest to printing position,

a return spring connected to said arm to return it and said bar tonormal position,

a power roll rotatably mounted on said frame,

and oscillatable roll cam means on said arm having accelerating anddecelerating portions which serially engage said roll first toaccelerate said arm and bar from zero to maximum velocity and then,after printing, to decelerate said arm and bar from maximum returnvelocity to zero at said headrest.

2. Mechanism in accordance with claim 1 wherein said accelerating anddecelerating portions are so arranged that said arm and bar are in freeflight from the end of acceleration to the arrival of said bar at theprinting position.

3. Mechanism in accordance with claim 1 wherein said roll cam meanscomprises two identical cams, and means mounting said cams on said armon a common axis.

4. Mechanism according .to claim 1 wherein said cam means comprises asingle element, said cam portions being joined by a flat which is spacedfrom said power roll when the mechanism is in normal condition.

5. Mechanism according to claim 1 provided with means including anovercentering spring connected to said arm and to said cam means foreffecting engagement between said decelerating portion and said powerroll after said type bar leaves the printing position.

6. Mechanism according to claim 5 wherein said last mentioned meansincludes a stop on said frame adapted to be engaged by a lug on said camwhich, upon engagement during the return movement of said arm, causesaid spring to overcenter.

7. Mechanism according to claim 1 including means operable in responseto manipulation of the writing machine for triggering said cam means toeffect engagement between said accelerating portion and said power roll.

8. Mechanism according to claim 1 wherein the point of engagementbetween said decelerating cam portion and said roll is at a point spacedfrom a line passing through the axes of said cam means and roll in thedirection of rotation of the roll and moves toward said line duringdeceleration.

9. A type bar action for an electric typewriter comprising, incombination,

a frame,

a type bar pivotally mounted on said frame,

means including an actuating arm for pivoting said bar from rest .toprinting position,

a return spring connected to said frame and said arm for returning saidarm to rest position,

a smooth surfaced power roll rotatably mounted on said frame,

a pair of oscillatable cams mounted on a common pivot on said armadjacent said power roll,

spring means interconnecting said cams and said arm to normally biassaid cams away from said power roll, one of said cams being engageablewith said power roll to accelerate said arm and bar from zero to maximumvelocity and the other of said cams being engageable with said powerroll to decelerate said arm and bar from maximum return velocity to zeroat the rest position of said arm and bar, and

means to eflect engagement of said accelerating cam with said powerroll.

References Cited by the Examiner UNITED STATES PATENTS 1,732,155 10/29Egli 197l7 1,963,285 6/34 Woodward 197-17 X 3,021,934 2/62 Enders l9717ROBERT E. PULFREY, Primary Examiner.

1. A TYPE BAR ACTION FOR A WRITING MACHINE IN COMBINATION, A FRAME, ATYPE BAR PIVOTALLY MOUNTED ON SAID FRAME, A HEADREST ON SAID FRAME FORSAID BAR, MEANS INCLUDING A PIVOTED ACTUATING ARM FOR PIVOTING SAID BARFROM SAID HEADREST TO PRINTING POSITION, A RETURN SPRING CONNECTED TOSAID ARM TO RETURN IT AND SAID BAR TO NORMAL POSITION, A POWER ROLLROTATABLY MOUNTED ON SAID FRAME, AND OSCILLATABLE ROLL CAM MEANS ON SAIDARM HAVING ACCELERATING AND DECELERATING PORTIONS WHICH SERIALLY ENGAGESAID ROLL FIRST TO ACCELERATE SAID ARM AND BAR FROM ZERO TO MAXIMUMVELOCITY AND THEN, AFTER PRINTING, TO DECELERATE SAID ARM AND BAR FROMMAXIMUN RETURN VELOCITY TO ZERO AT SAID HEADREST.